In-situ method and apparatus for measuring fluid resistivity

A process chamber, comprising:

• a plurality of walls defining an internal volume;
• a fluid source configured to provide a process fluid to the internal volume;
• a measurement probe fluidically coupled to the fluid source, the measurement probe comprising:
• an upstream fluid conduit coupled to a first end of the fluid source;
• a downstream fluid conduit coupled to a second end of the fluid source;
• and
• a measuring section, comprising:
• a metal rod;
• and
• a ground electrode coaxial with the metal rod, wherein the upstream fluid conduit is coupled to a first end of the ground electrode, and the downstream fluid conduit is coupled to a second end of the ground electrode;
• and
• a contact electrically coupled to the ground electrode, the contact is configured to receive a metric from the measuring section, the metric corresponding to a resistivity of the process fluid, wherein the measuring section is configured to provide a metric of resistivity of a fluid based upon a surface area of the ground electrode within a space between the metal rod and the ground electrode and a distance between the metal rod and the ground electrode when a voltage is applied to the metal rod.

A method of detecting contamination in a process fluid, comprising:

• determining an electrical resistivity of a process fluid entering or exiting a process chamber, wherein the process chamber is disposed within a recirculation path, the process fluid circulating within the recirculation path, wherein a measurement probe is fluidically coupled to the recirculation path, the measurement probe comprising:
• a measuring section, comprising:
• a metal rod;
• and
• a ground electrode coaxial with the metal rod, the metal rod and the ground electrode defining a space therebetween for flowing the process fluid through the recirculation path;
• outputting an electrical metric from the measurement probe corresponding to the electrical resistivity of the process fluid;
• comparing the electrical resistivity to a threshold, the threshold corresponding to a level of contamination of the process fluid, wherein the measuring section is configured to provide a metric of resistivity of a fluid based upon a surface area of the ground electrode within the space and a distance between the metal rod and the ground electrode when a voltage is applied to the metal rod;
• and
• replacing one or more recirculation components disposed in the recirculation path, if the threshold is met or exceeded.